Solenoid structure



SOLENOID STRUCTURE William A. Ray, North Hollywood, Calif assignor to General Controls Co., Glendale, Cahfi, a corporation of California Application November 3, 1952, Serial No. 318,472 4 Claims. (Cl. 317-191) My present invention relates to electromagnetic operators of the plunger or solenoid type, and more particularly to one especially adapted for operating fluid control valves.

The solenoid operator of this invention is more particularly adapted for use with direct current. In directcurrent solenoid operators of conventional construction which include a stop for the plunger, the cooperating ends of these parts are usually conformably coned to provide a large air-gap therebetween so that the magnetic pull is increased when the plunger is near the stop. One object of this invention is to improve this type of solenoid operator, and I accomplish this object by making the cooperating end surfaces of the plunger and the stop conformably convex and concave, and preferably substantially hemispherical.

In a solenoid operator for a valve, the guide tube in which the plunger reciprocates is usually closed at its outer end and secured to the valve casing so as to provide a packless seal for the plunger. It is another object of this invention to improve this plunger tube, and I accomplish this object by forming the closed end of the tube of material of generally the same thickness as that of the side wall of the tube, and by curving the end, preferably so that it is substantially hemispherical.

It is a more specific object of this invention to provide a solenoid valve structure wherein the head of the plunger is generally hemispherical, the end of the plunger tube is relatively thin and shaped to conform to the curvature of the plunger head, and the stop member has a depression fitting the rounded tip of the plunger tube.

For full understanding of the invention, and further appreciation of its features and advantages, reference is to be had to the following detailed description and accompanying drawing, and to the appended claims.

The single figure of the drawing is a sectional view of a solenoid valve embodying the invention.

In the drawing the numeral 11 indicates a valve casing having an inlet 12 and an outlet 13. In the top of the casing is a large recess 14 which is in continuous communication with the inlet 12 by way of an opening 15 at the bottom of the recess. Extending centrally downwards from the bottom of recess 14 is another recess 16 which is threaded to receive a member 17 having a port 18. At its lower end the recess 16 is connected by an opening 19 to the outlet 13, so that when the top of member 17 is uncovered fluid can pass from inlet 12 through opening 15, recess 14, port 18, recess 16 and opening 19 to the outlet 13.

The upper end of recess 14 is closed by a threaded member 20 which forms the base of an iron-clad solenoid frame comprising a cylindrical side wall 21 and a top wall 22; these parts being of magnetic material and secured together as by press-fitting and welding. Threaded in a central opening through the top wall 22 is a cylindrical stop member 23, of magnetic material, whose bottom surface is recessed to conform to the hemispherical States Patent "ice top 24' of a plunger tube 24, of nonmagnetic material, which projects upwards through a central opening in the base 20, which opening is enlarged at its lower end to permit flaring of the bottom portion of the tube; the tube being sealed in the opening by welding at its junction with the top surface of the base. A wrench socket 25 is provided for screwing the stop member 23 into firm engagement with the plunger-tube top 24. Surrounding the stop member and the upper part of the plunger tube is an energizing coil 26.

Fitting relatively loosely within tube 24 is a cylindrical plunger 27, of magnetic material, having a substantially hemispherical top or protuberance 28 which conforms to the curvature of the socket defined by the adjacent inner surface of the plunger-tube top 24. Attached to the bottom of the reduced lower end portion of plunger 27, by means of a crimped ring 29, is a closure disk 30 which cooperates with a seat 31 formed by the top surface of the port member 17. Biasing the plunger downwards, and closure 30 toward seating position, is a rod 32 slidable in an axial opening through the plunger and urged upwards by the force of a spring 33 in a lower enlargement of the rod-opening and compressed between the closure 30 and a cupped member 34 on the lower end of the rod. To prevent entrapment of fluid in the spring-recess a vent 35 is provided. When the solenoid is energized by passage of current through coil 26 the plunger 27 is attracted to its stopped position in engagement with the top wall 24' of the plunger tube, and closure 30 is raised from its seat 31 so that fluid can pass through the valve.

Due to its rounded top, the plunger tube is capable of withstanding high pressure to which it may be subjected by the fluid controlled by the valve, regardless of any support provided by the stop member; the tube structure having considerable utility in the organization independent of the stop.

The end wall of the plunger tube, being of nonmagnetic material, froms the air-gap between the plunger and the stop when the plunger is in attracted position, and serves as a separator which prevents sticking of the plunger due to residual magnetism. These magnetic factors, in addition to the fluid pressure, should therefore be considered in determining the proper thickness of the end wall of the tube.

Due to the large, relatively unbroken, air-gap area good holding force is produced. The air-gap is not appreciably changed with slight rocking of the plunger because of the rounded surfaces, and wear of the surfaces is uniform and has no tendency to effect mechanical sticking of the plunger. Especially when the plunger stroke is relatively short (of the order of that indicated in the drawing), I have found that the hemispherical construction of the plunger and stop is superior to the conventional conical construction of direct-current solenoids in the production of tractive force.

The curvature of the cooperating rounded parts may be other than hemispherical, but substantially hemispherical curvature is preferred. According to the broader phases of this invention the end wall of the plunger tube may be concave, instead of convex, and the opposing surfaces of the plunger and stop member conformably concave and convex, respectively; however, the arrangement substantially as shown in the drawing, wherein the stop member and the plunger tube are of the same diameter, is preferred for ease of production and also because it appears to afford a better path for the magnetic flux.

The specific embodiment of my invention herein shown and described is therefore to be considered as illustrative and not as limiting the scope of the appended claims.

I claim as my invention:

1. In a solenoid structure of the type which comprises a frame providing a stop member mainly of magnetic material; a plunger member, of magnetic material, mounted for attraction toward said stop member; and a coil arranged and adapted, upon passage of current therethrough, to eifect said attraction of the plunger member; said members having surfaces intercngageable when the plunger member is attracted-the improvement consisting in that said interengageable surfaces of the members define, respectively, a substantially hemispherical protuberance and a socket for receiving said protuberance and conforming thereto in curvature 2. A solenoid structure according to claim 1 wherein said protuberance and said socket are defined by said interengageable surfaces of the plunger member and of the stop member, respectively.

3. A solenoid structure according to claim 1 and ineluding a tube, of thin nonmagnetic material, freely surrounding the plunger member and having a closed endportion interposed between said interengageable surfaces of the members and conforming thereto in curvature, and means for mounting said tube with said closed end-portion thereof in engagement With said surface of the stop member.

4. A solenoid structure according to claim 3 wherein said protuberance and said socket are defined by said interengageable surfaces of the plunger member and of the stop member, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 1,460,517 Stevens July 3, 1923 1,830,628 Trombetta Nov. 3, 1931 2,102,761 Strobel Dec. 21, 1937 2,351,140 McCloy June 13, 1944 2,374,513 Vieth u Apr. 24, 1945 2,394,105 Rice Feb. 5, 1946 2,476,794 Austin July 19, 1949 FOREIGN PATENTS 820,952 France Nov. 24, 1937 742,732 Germany Dec. 10, 1943 657,082 Great Britain Sept. 12, 1951 

